Nuclear Spin Selective Torsional States: Implications of Molecular Symmetry

Belz, S.; Deeb, Omar; González, Leticia; Grohmann, Thomas; Kinzel, Daniel; Leibscher, M.; Manz, J.; Obaid, Rana; Oppel, Markus; Xavier, F. George D.; Zilberg, Shmuel

doi:10.1524/zpch.2013.0385

Cited by 9 publications

(10 citation statements)

References 85 publications

(166 reference statements)

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“…The last four columns give our results for the maximum tunneling velocity max ṽ, the time-averaged tunneling velocity avg ṽ, the tunneling time τ and the time tB needed for tunneling through the top of the potential barrier, as defined in equations (55,56), (38), and (58,59), respectively. (5), (12), for the Gaussian model (16) and for the Mathieu model (33), as well as for a scaled Gaussian model. Top: tunnel splitting ∆E = 4j(0, τ /4) for cyclic models (∆E = 2j(0, τ /4) for non-cyclic models).…”

Section: Applications Discussion and Conclusionmentioning

confidence: 99%

“…For example, F. Hund in his fundamental paper [1] investigated tunneling from one enantiomer to the opposite one, with application to the torsional (cyclic) dynamics of H 2 O 2 . Below we shall consider complementary prototypical examples of molecules which may tunnel in cyclic symmetric double well potentials by torsional motions of two fragments about a connecting axis [15][16][17][18][19]. Alternatively, we shall also consider molecules which exhibit non-cyclic tunneling -the prototypical examples are tunneling of ammonia and semibullvalene along the coordinates which describe inversion [17,20] and Cope rearrangment [21][22][23][24], respectively.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 3: Dependence of characteristic quantities on dimensionless action parameter β, eqns. (5),(12), for the Gaussian model(16) and for the Mathieu model(33), as well as for a scaled Gaussian model. Top: tunnel splitting ∆E = 4j(0, τ /4) for cyclic models (∆E = 2j(0, τ /4) for non-cyclic models).…”

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confidence: 99%

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Maximum tunneling velocities in symmetric double well potentials

et al. 2014

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We consider coherent tunneling of one-dimensional model systems in non-cyclic or cyclic symmetric double well potentials. Generic potentials are constructed which allow for analytical estimates of the quantum dynamics in the non-relativistic deep tunneling regime, in terms of the tunneling distance, barrier height and mass (or moment of inertia). For cyclic systems, the results may be scaled to agree well with periodic potentials for which semi-analytical results in terms of Mathieu functions exist. Starting from a wavepacket which is initially localized in one of the potential wells, the subsequent periodic tunneling is associated with tunneling velocities. These velocities (or angular velocities) are evaluated as the ratio of the flux densities versus the probability densities. The maximum velocities are found under the top of the barrier where they scale as the square root of the ratio of barrier height and mass (or moment of inertia), independent of the tunneling distance. They are applied exemplarily to several prototypical molecular models of non-cyclic and cyclic tunneling, including ammonia inversion, Cope rearrangment of semibullvalene, torsions of molecular fragments, and rotational tunneling in strong laser fields. Typical maximum velocities and angular velocities are in the order of a few km/s and from 10 to 100 THz for our non-cyclic and cyclic systems, respectively, much faster than time-averaged velocities. Even for the more extreme case of an electron tunneling through a barrier of height of one Hartree, the velocity is only about one percent of the speed of light. Estimates of the corresponding time scales for passing through {the narrow domain just} below the potential barrier are in the domain from 2 to 40 fs, much shorter than the tunneling times

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Section: Applications Discussion and Conclusionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Maximum tunneling velocities in symmetric double well potentials

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“…At very low temperature, CCD has four different nuclear spin isomers populated. 49 Two groups of nuclear spin isomers can be discriminated via their different torsional dynamics in the excited state. 46 This can be used to change the equilibrium ratio of both isomer groups by using carefully optimized ultrashort laser pulses in a pump−dump like scenario.…”

Section: Introductionmentioning

confidence: 99%

“…At very low temperature, CCD has four different nuclear spin isomers populated . Two groups of nuclear spin isomers can be discriminated via their different torsional dynamics in the excited state .…”

Section: Introductionmentioning

confidence: 99%

Controlling the Excited-State Dynamics of Nuclear Spin Isomers Using the Dynamic Stark Effect

2016

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Stark control of chemical reactions uses intense laser pulses to distort the potential energy surfaces of a molecule, thus opening new chemical pathways. We use the concept of Stark shifts to convert a local minimum into a local maximum of the potential energy surface, triggering constructive and destructive wave-packet interferences, which then induce different dynamics on nuclear spin isomers in the electronically excited state of a quinodimethane derivative. Model quantum-dynamical simulations on reduced dimensionality using optimized ultrashort laser pulses demonstrate a difference of the excited-state dynamics of two sets of nuclear spin isomers, which ultimately can be used to discriminate between these isomers.

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